DESCRIPTION (verbatim from the applicant's abstract): Dinoflagellates are prodigious producers of polyketides and some of the largest and most complex polyketides are produces by these organisms. Recently, the functional expression of polyketide biosynthetic pathways has led to several strategies for producing rare or novel polyketides. These strategies include, combinatorial expression, and mutations that knockout or restore activity. The functional expression of dinoflagellate biosynthetic pathways or the coupling of these pathways with bacterial systems could lead to unprecedented biosynthetic capabilities for the engineered biosynthesis of novel polyketides. The first goal of this project is the identification and mapping of polyketide pathways in the dinoflagellate Prorocentrum lima. To accomplish this goal, we must employ strategies that will permit the identification of the gene(s) in an extremely large genome (1011 bp). While undoubtedly a challenge, preliminary data indicate that it is not insurmountable. The second goal is to develop methods that would permit the functional identification of the pathways. Because no genetic transformation systems have been developed for dinoflagellates, we view this work as somewhat high risk, however the potential benefits are great. The identification of the okadaic acid polyketide synthase gene is the first step towards our longer term goal of cloning and sequencing the entire biosynthetic pathway, and utilizing dinoflagellate biosynthetic genes for programmed biosynthesis of novel compounds.